Roasting-furnace.



PATENTED APR. 4, 1905. W R. INGALLS. ROASTING FURNACE. APPLICATION FILEDFEB. 15, 1904.

3 SHEETS-SHEET l.

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PATENTED APR. 4, 1905.

W. R. INGALLS. ROASTING FURNACE APPLICATION FILED FBB.15, 1904.

3 SHEETSSHEET 2.

PATENTED APR. 4,.1905.

W. vR. INGALLS. ROASTING FURNACE APPLICATION FILED FEB.15, 1904.

, UNITED STATES Patented April 4, 1905.

PATENT OFFICE.

ROASTlNG-FURNACE.

SPECIFICATION forming part of Letters Patent No. 786,567, dated April 4,1905.

I I Application filed February 15, 1904. Serin.lNo.193.622.

T0 on whom it may concern.-

Be it known that I, WALTER'RENTON IN- GALLS, a citizen of the UnitedStates, residing at. Lynn. in the county of Essex, Commonwealth ofMassachusetts; have inventednew and usefullmprovements inRoasting-Furnaces, of which the following is a specification.

My invention relates particularly to what is known as the McDougall?type of furnace; and, its objects are to provide an improved rotarystirrer for use in such furnaces and to adapt the furnace to a muflieform,

whereby it may be used to produce a strong and uncontaminated sulfurousgas from ores which require the aid of extraneous fuel in theirroasting.

Furnaces of the McDougall type consist of a vertical cylinder of brick,usually incased with a jacket of iron, with arched hearths havingdischarge-openings alternately near the center and periphery and acentral revolving shaft with horizontal radial stirringarms, which areprovided with teeth or rabbles placed at an angle to the arm. The teethof the arms on the even-numbered hearths are set ina direction oppositeto that of the oddnumbered, so that on alternate hearths they act topush the ore toward the center or toward the side, respectively. The oreis thus worked through the furnace, dropping from hearth to hearth, anddischarged linally from the lowest hearth. At the same time the airnecessary for combustion .of the ore passes upward in the reversedirection to the downward movement of the ore. The heat re quired inroasting certain ores is such that the central shaft, the arms, and therabbles there'- on have but ashortlifo and are likely to be quicklydisabled. For tliis reason the stirring-arms are commonly maderemovable, and in various furnaces of this type means are provided forcooling the arms by circulation of a current of airor water therein. Inconstructing mufile furnaces' of the Me- Dougall type com bustion-fluesare interposed between the hearths, so that the latter will be heated byflames traversing the flues without coming in contact with the ore onthe hearths.

tal section on the line H H ofFig. 6.

it has been commonly the practice to cause the flames to traverse thecombustion-Hues dia-' metrically, rising from one flue to the nextavertical section of the furnace through the center. Figs. 2 and 3 arerespectively horizontal sections on the lines B B and A A of Fig. 1.Fig. 4 is a vertical half-section through the combustion-fines and sixthmufiie on the line I) l) of Figs. 2 and 3. Fig. 5 is a verticalhalf-section through the combustion-fines and sixth muffle on the line CG of Figs. 2 and 3. Fig. 6 is a vertical section through the center ofthe revolving shaft and stirringarms on the line'K K of Fig. 11. Fig. 7is a section on the line F F of Fig. 6. Fig. 8 is a section on the lineL Lof Fig. 6. Fig. 9 is an end view of a stirring-tooth, and Fig. 10 isa front view of the same. Fig. 11 is a horizon- Fig. 12 is a section onthe lines E E of Fig. 6.

Like numerals refer to like parts throughout the several drawings.

Referring to the drawings, 30 represents the circular wall of thefurnace, which stands served by the iron casing 29. The lowest twohearths are formed of refractory tiles 32, laid on the ledges 34:, andthe tire-brick partitions 33. In this way the furnace shownis dividedinto six mufiies or roastirig-chambers 1, 2, 3, 4, 5, and 6 and twocombustion-dues 7 and 8. The combustion-fines are shown only under thefifth and sixth hearths, which in view of the thick side walls 30 andthe means for supplying preheated air, to be referred to subselnfurnaces of this type previously designed 1 quently, may be all that isnecessary in furnaces for roasting certain ores; but fiues may bearranged under the upper hearths in the same manner, if required.

The ore to be roasted is fed from the hopper 9 by a screw 10 to thetopmost hearth. The central revolving shaft, supported by ballbearings16 on the pedestal 27 and revolved by the spur-wheel 17 and a worm-wheelor pinion, (not shown in the drawings,) works the ore inwardly on theuppermost hearth until it drops through the central hole to the secondhearth, whereon it is worked outwardly, dropping through peripheralholes (not shown in the drawings, being outside of the planes thereof)to the third hearth, and so on, being finally discharged from the sixthhearth. The sulfurous gas arising from the burning ore passes upward ina direction opposite to the travel of the ore and is finally conveyedaway through an opening in the top of the furnace (not shown in thedrawings, being outside the planes thereof) in a manner quite familiarto those who are acquainted with the art. The fifth and sixth hearthsare heated from below by flames in the lines 8 and 7. The flames may beproduced from a fireplace or by the combustion of oil or gas in thefines. In the design shown in the accompanying drawings gas-firing iscontemplated. Gas is admitted through the canal into the flue 8, whereinit burns with air admitted through the port 37. The burning gastraverses the flue in the direction of the arrows in Fig. 2, making thecircuit around the partition 33 until stopped by the partition 38, whichdeflects it into the ducts 39, communicating with the flue 7. In flue 7the burning gas passes around the partition 33 in the direction shown bythe arrows in Fig. 3 and escapes through the canal 40 to the chimney.The circular direction of the burning gas through the flues 8 and 7,which is affected by means of the partitions 38, gives it a longercourse in which to impart its heat to the muflies 5 and 6 than if itmerely passed diametrically through the fines 8 and 7. This, inconnection with a correct design of the furnace in other respects, re-

, duces the number of flues required for any specific ore, and thus theheight of the furnace, and consequently its first cost. The dimensionsof the flues 7 and 8 and the various canals, ports, and ducts 36, 37,39, and 40 are of course proportioned to the volume of gas that must beburned and the combustion products thereof.

The stirring mechanism consistsof a castiron shaft composed of an outertube 12 and an interior tube or flue 13, the latter being convenientlymade of rectangular form, although not necessarily so. The interior tube13 is made separately from the outer tube 12 and is inserted inside ofthe latter, being secured at the bottom by the tight joint 54 and heldin proper position at the top by the fins 53. Through holes in the shaftare passed the main stirring-arms 42, while the outer arms 41 onlyconnect with the shaft. In alternate hearth-chambers or mufiies the armsare set at right angles to those'next above and below. The arms 42,which are shown as tubular in form, but may be of any other suitablehollow shape, pass clear through the central shaft, making a tight jointwith the inner portion 13 thereof. There are apertures 48 at the centerand 43 near the ends of these arms. The ends are closed by the plugs 44,which are secured by the bolts 45. Over these arms are passed the hollowarms 41, which set into the holes 47 of the outer shell 12 of thecentral shaft, which is there thickened sufficiently to give agoodbearing. In order to make a tight joint and for ease in insertion andremoval, the hole 47 is made slightly tapering, and the end of the arm41 is tapered to correspond. The arms 41 may be cast with fins 51, overwhich the stirring teeth are slipped, as shown in Fig. 9; but severalother simple ways of attaching the stirring-teeth are available. Thearms 41 and the stirringteeth strung on them are secured by the wedge46, driven through the plug 44 in the ends of the arms 42. Instead ofthe wedge the end of the plug 44 maybe threaded and the whole secured bya nut. Any tendency of the arm 42 to turn over is'prevented by the fin49 at the center, which also strengthens the arm at that point. In thisway the stirring-teeth 56 are easily removable from the outer arm 41,the outer arm 41 is easily removable from the inner arm 42, and theinner arm 42 iseasily removable from the central shaft. After all thearms have been removed and the collars 28 have been unbolted the centralshaft itself may be removed from the'furnace by simply lifting it out.

In operation a current of air from a canal under the furnace is forcedthrough the tube 20 into the inner flue of the central shaft, from whichit passes through the apertures 48 into the arms 42. Going to the endsof the arms the air passes through the apertures 43 into the spacebetween the inner and outer arms, through Which'it returns to thecentral shaft, rising then through the outer flue of the latter or thespace between the shells 12 and 13 and being thence conveyed through thepipe 23 to the duct 24 in the side wall of the furnace, whereby it isdischarged through the port 25 into the lowest muflie. In this way airis constantly circulated through the parts of the stirring mechanismexposed to intense heat, and the arrangement is such that the mainsupporting -partsviz., the arms 42 and the inner portion 13 of thecentral shaftare exposed to the currentof cooling-air, both inside andoutside, which it is conceived will greatly promote their. durability.The air which becomes heated in cooling the stirring mechanism isreturned to the furnace, wherefore there is no loss of heat, and,indeed, there developed in certain may be an increase in the efficiencyof the furnace, since some surplus heat which may be portions will betransferred in the form of hot air to the lowest muffle, where the mostextraneous heat must be supplied. The furnace may be operated withoutthis air-return and even with only a natural draft; but the arrangementshown in the accompanying drawings is preferable. Communication betweenthe inner and outer fines of the central shaft except through thestirring-arms is prevented by means of the stop 50 and the tight joint54. Uonnection with the external air is shut off by means of the liquidseals and 57. The central shaft is supported at the top by the bearing21, secured to the beams 22.

It will be observed that my invention provides a stirring mechanismwhich in addition to advantages above referred to has certain others ofimportance. The main stirringarms being of one piece andcounterbalanced, there are fewer strains on the central shaft and thearm itself can be made .more rigid weight for weight. There .are noprojecting hubs on the central shaft, which is thereby simplified inconstruction. In removing either of the stirring-arms they can be pulledout horizontally, thereby saving so much height in the roasting-chambersas is necessary to lift the arms in order to unlock them in certainfurnaces.

Obviously the stirring mechanism of my invention herein described may beused in connection with a furnace without the combustion-flues hereinshown.

What I claim as my invention, and desire to secure by Letters Patent, is

1. A roasting-furnace comprising two or more superimposed hearths, fluesunder two or more of said hearths, ducts connecting said flues, means tocause the gas burned in said fines to pass successively through them ina circular direction; and a rotary stirring mechanism with armsprojecting over the hearths, said stirring mechanism consisting of acentral vertical shaft with an interior flue, hollow horizontal armspassing entirely through said shaft and communicating with said interiorflue by suitable apertures, the portions of said arms exterior to thecentral vertical shaft being inclosed by other hollow arms. so as toleave an open space between the inner and outer arms, and means forcirculating a cooling medium through the shaft and arms.

2. A rotary stirring mechanism comprising a central vertical shaft withan interior flue, and a hollow horizontal arm, subdivided into flues,passing entirely through saidshaft.

3. A rotary stirring mechanism comprising a central vertical shaft withan interior flue, hollowhorizontal arms passing entirely through saidshaft, the portions of said arms exterior to the central vertical shaftbeing inclosed by other hollow arms, so as to leave an open spacebetween the inner and outer arms, said outer arms being supported bysaid inner arms, and means for circulating a cooling medium through theshaft andarms.

In witness whereof I have hereunto set my hand in the presence of twosubscribing wit- HGSSGS.

WALTER BENTON INGALLS. Witnesses:

WILLIAM W. LUMMUS,

EDWARD J. CoNNELL.

